Stocks higher, but volatile, after Bernanke speaks

Stocks gyrated after Federal Reserve chairman Ben Bernanke spoke on Friday morning. They first gave up their morning gains, then bolted to their highs for the day, before settling in-between.

The Dow Jones industrial average ended the day up 90.13 points at 13,090.84.

A half-hour after trading began, Bernanke declared that the Fed is ready to take more action to help an economy that's "far from satisfactory."

Stocks rebounded once investors parsed his comments. At one point the Dow was up as many as 151 points.

The Standard & Poor's 500 index closed up by 7.10 points at 1,406.58. The Nasdaq rose 18.25 points to close at 3,066.96.

The Dow finished the month of August up by 0.8 percent. The S&P 500 rose more than 2 percent for the month, and the Nasdaq rose more than 4 percent.

Oil prices jumped $1.81 to $96.43 per barrel on the New York Mercantile Exchange. Natural gas and heating oil both rose more than 1 percent. Facebook fell 5.4 percent to $18.06, a new low.

Stocks rose in nine out of 10 industry groups in the S&P 500.